It is difficult to conceive the subject invention in this case from the prior art as the subject invention in this case and the prior art differ in terms of target product, applied technology, composition, and effect even though it was initially viewed to be easily conceived from the ‘manufacturing process for collagen sheet for wound dressing by treating fish scales with hydrochloric acid’ of the prior art as ‘decelluarization’ of fish scales were commonly present in both inventions in the decision of rejection from the patent examiner and the decision of IPTAB.